Rising damp questions, answered

This is the hardest call in this city. Cold still air and high morning humidity mean both turn up in the same house. Condensation appears on cold surfaces and around windows, is worst in closed-up rooms, and leaves mould but no salt. Rising damp leaves a level line low on the wall with salt below it. It is worst after a wet winter, but the line and the salt stay all year, which condensation does not do.

Because the two fixes have nothing in common. Condensation is solved with ventilation, heating and moving furniture off cold walls, often for very little money. Rising damp needs a barrier and salt removal. Treating one as the other wastes the whole budget, which is why the assessment comes first.

Up to two hours on site and a written diagnosis. Moisture is read at intervals up the wall instead of one spot, and outside ground levels and drainage are checked. Where the masonry calls for it, we also take a small mortar sample to test it. Treatment is quoted separately, after the cause is known.

Yes. Sandstone is porous and many Hobart houses were built before damp courses were standard, so there may be nothing in the wall to fail. Sandstone also decays from salt rather than cracking, so the damage shows as the face crumbling away. It takes treatment differently to brick and generally needs more of it.

Usually yes, but the method matters and so does the paperwork. Cement render and modern pointing trap moisture in soft old stone and accelerate the decay, which is how well-meant repairs cause damage. Lime-based materials let the wall breathe. Any work on a listed property may need approval, and that is the owner's to obtain.

On solid masonry, rarely. It seals the face, the water rises higher or moves sideways, and the salt builds up behind it until the render blows off in sheets. Taking failed cement render off is often part of the repair.

Because water arrives from uphill. On a sloping Hobart block the ground on the high side can sit well above the floor level inside, and the wall holding that ground back is wet from behind rather than from below. That is lateral damp. It is fixed with drainage where the ground can be dug back, or by tanking the wall where it cannot, not with an injected damp course. Tanking is priced on the cost page.

Months. Stopping the rise is quick, drying is not, and the salt already in the masonry never leaves on its own. Expect the finish work to happen well after the barrier goes in, and treat any promise of a fast result with suspicion.

Generally no. Policies usually exclude gradual deterioration, and rising damp is gradual. A sudden leak is a different matter. Check your own policy, because we cannot tell you what yours covers.

We do, with one specialist on the job from the assessment to the finish. Tasmania does not license damp proofing as a trade. Plumbing and drainage are licensed, so any drainage part of the job goes to a licensed plumber. Any licence you are shown can be checked on the register of Consumer, Building and Occupational Services.

Related but not identical. Mould grows where surfaces stay wet, so it can come from rising damp, condensation or a leak. Cleaning it without fixing the water is temporary. We are not medical people — if anyone in the house is unwell, see a doctor.

Sometimes that is the honest answer for a short stay, and the assessment will say so. What does not work is ignoring salt damage to soft stone, because the face of the wall keeps going and that damage is not reversible.